One more addition to this thread.
The 'original' tri bike, the Quintana Roo Superform, is often seen for sale on eBay and other internet sites. It's now fairly unloved as it needs 26"/650 wheels and tyres and has an relatively unfashionable steel frame. However it offers the kind of geometry (a steep seat-tube angle) of any modern tri bike, and is specifically designed that way, so handles better (and safer) and fits better than a road bike frame with a FF seat post.
Well worth looking out for if you are on a tight budget.
